Tìm x biết -x+8=-17

a) -x + 8 = -17

⇔ -x = -17 - 8

⇔ -x = -25

⇔ x = 25

b) 35 - x = 37

⇔ x = 35 - 37

⇔ x = -2

c) -19 - x = -20

⇔ x = -19 + 20

⇔ x = 1

d) x - 45 = -17

⇔ x = -17 + 45

⇔ x = 28

e) |x + 3| = 15

⇔ \(\left[{}\begin{matrix}x+3=15\\x+3=-15\end{matrix}\right.\)

⇔ \(\left[{}\begin{matrix}x=15-3\\x=-15-3\end{matrix}\right.\)

⇔ \(\left[{}\begin{matrix}x=12\\x=-18\end{matrix}\right.\)

f) |x - 3| - 16 = -4

⇔ |x - 3| = -4 + 16

⇔ |x - 3| = 12

⇔ \(\left[{}\begin{matrix}x-3=12\\x-3=-12\end{matrix}\right.\)

⇔ \(\left[{}\begin{matrix}x=12+3\\x=-12+3\end{matrix}\right.\)

⇔ \(\left[{}\begin{matrix}x=15\\x=-9\end{matrix}\right.\)

k) 26 - |x + 9| = -13

⇔ |x + 9| = 26 + 13

⇔ |x + 9| = 39

⇔ \(\left[{}\begin{matrix}x+9=39\\x+9=-39\end{matrix}\right.\)

⇔ \(\left[{}\begin{matrix}x=39-9\\x=-39-9\end{matrix}\right.\)

⇔ \(\left[{}\begin{matrix}x=30\\x=-48\end{matrix}\right.\)